Double Asymptotic Structures of Topologically Interlocked Molecules.

The mean square size of topologically interlocked molecules (TIMs) is presented as a linear combination of contributions from the backbone and subcomponents. Using scaling analyses and extensive molecular dynamics simulations of polycatenanes as a typical example of TIMs, we show that the effective exponent ν(m) for the size dependence of the backbone on the monomer number of subcomponent m is asymptotic to a value ν (∼0.588 in good solvents) with a correction of m-0.47, which is the same as for the covalently linked polymer. However, the effective exponent for the size dependence of subcomponents on m is asymptotic to the same value ν but with a new correction of m-1.0. The different corrections to the scaling on the backbone and subcomponent structure induce a surprising double asymptotic behavior for the architecture of the TIMs. The scaling model that takes into account the double asymptotic behavior is in good quantitative agreement with the simulation result that the effective exponent for the size dependence of TIMs on m increases with the subcomponent number n. The full scaling functional form of the size dependence on m and n for polycatenanes in a good solvent is well described by a simple sum of two limiting behaviors with different corrections.

Lifestyle Risk Factors and the Population Attributable Fractions for Overweight and Obesity in Chinese Students of Zhejiang Province.

Objectives: To assess the relationship between modifiable lifestyle factors and risk of overweight/obesity in Chinese students, and to evaluate the predicting prevalence of overweight if the lifestyle risk factors were removed. Methods: A cross-sectional survey was conducted among 40,141 students in grade three and above (8-24yrs) in 2019 in Zhejiang Province, China. Physical examination was performed, and a self-administered questionnaire was used to collect lifestyle information, including dietary behavior, physical activity, TV watching, sleeping, smoking, drinking, and tooth-brushing habits. Logistic regression models were performed to assess the relationship between overweight/obesity and a series of lifestyle factors. Population attributable fractions (PAFs) were used to calculate the predicting prevalence of overweight/obesity if lifestyle risk factors were removed. Results: The prevalence of overweight/obesity of participants was 25.5% (male 32.3%, female 18.1%). Overweight/obesity were associated with adverse lifestyle factors, such as watch TV ≥1 h/day (OR = 1.14, 95% CI: 1.11-1.22), insufficient sleep (OR = 1.14, 95% CI: 1.11-1.22), and irregular toothbrushing habits (OR = 1.19, 95% CI: 1.01-1.39). Based on the calculated PAFs, the predicted prevalence of overweight/obesity would decline moderately if lifestyle factors were modified, with the magnitudes of decrease vary by sex, age and residence. Generally, a larger reduction was estimated if the sleeping time was increased and TV time was reduced, with the prevalence of overweight/obesity decreased by 1.1% (95% CI: 0.7, 1.5%) and 0.9% (95% CI: 0.6, 1.2%), respectively. Conclusions: Predicted prevalence of overweight/ obesity in Chinese students may decrease if modifiable lifestyle risk factors were removed. The attributable risk for obesity of lifestyle behaviors varied in age, sex and residence groups. The findings of this study may provide insights for planning and optimizing future obesity intervention endeavors.

Cooperative translocation dynamics of biopolymer chains through nanopores in a membrane: Slow dynamics limit.

The cooperative translocation dynamics of two complementary single-stranded DNA chains through two nanopores located in a membrane is investigated theoretically. The translocation process is considered to be quasi-equilibrium, and then under the limit of slow dynamics the average translocation times are numerically presented under different conditions. It is shown that the effects of the chemical potential gradient, the recombination energy and the distance between the two nanopores on the cooperative translocation are significant. The present model predicts that the cooperative translocation of such two chains can shorten the translocation time, reduce the backward motion and thus improve the translocation efficiency.

Study on a novel antibacterial light-cured resin composite containing nano-MgO.

A new type of photocurable resin composite containing nano-MgO was synthesized in order to reduce the occurrence of secondary caries. Different mass ratios (0 %, 1 %, 2 %, 4 %, 8 %) of nano-MgO were added into resin composites. The antibacterial properties of nano-MgO powder and modified resin composites against Streptococcus mutans (S. mutans) were detected by antibacterial ring test and film contact test, respectively. Compressive strength (CS) and wear resistance were determined by a universal testing machine and an abrasion test machine. The results indicated that antibacterial activity and wear resistance of resin composites containing nano-MgO were superior to the control group (p < 0.05). The antibacterial rate reached as high as 99.4 % when the mass ratio of nano-MgO was 8 %. However, the CS values tended to decline as the content of nano-MgO increase. Hence, the addition of nano-MgO showed excellent antibacterial property to resin composites and enhanced wear resistance, but was detrimental to their mechanical properties.

Chinese guidelines for the diagnosis and treatment of hand, foot and mouth disease (2018 edition).

BACKGROUND: Hand, foot, and mouth disease (HFMD) is a common infectious disease in childhood caused by an enterovirus (EV), and which is principally seen in children under 5 years of age. To promote diagnostic awareness and effective treatments, to further standardize and strengthen the clinical management and to reduce the mortality of HFMD, the guidelines for diagnosis and treatment have been developed. METHODS: National Health Commission of China assembled an expert committee for a revision of the guidelines. The committee included 33 members who are specialized in diagnosis and treatment of HFMD. RESULTS: Early recognition of severe cases is utmost important in diagnosis and treatment of patients with HFMD. The key to diagnosis and treatment of severe cases lies in the timely and accurate recognition of stages 2 and 3 of HFMD, in order to stop progression to stage 4. Clinicians should particularly pay attention to those EV-A71 cases in children aged less than 3 years, and those with disease duration less than 3 days. The following indicators should alert the clinician of possible deterioration and impending critical disease: (1) persistent hyperthermia; (2) involvement of nervous system; (3) worsening respiratory rate and rhythm; (4) circulatory dysfunction; (5) elevated peripheral WBC count; (6) elevated blood glucose and (7) elevated blood lactic acid. For treatment, most mild cases can be treated as outpatients. Patients should be isolated to avoid cross-infection. Intense treatment modalities should be given for those severe cases. CONCLUSION: The guidelines can provide systematic guidance on the diagnosis and management of HFMD.

[The risk factors of reflux esophagitis in Shandong farmers].

OBJECTIVE: To investigate the risk factors of reflux esophagitis (RE) in farmers of Shandong province. METHODS: Five hundred and fifty six peasants (aged from 34 to 90 years old) were randomly selected from the rural general population in Yantai area, Shandong province. All participants received a face to face interview for relating clinical symptoms. Upper gastrointestinal endoscopic and histopathologic examination were carried out. RESULTS: 101 (18.2%) patients were diagnosed endoscopically as RE. According to Los Angeles Classification system, the distribution of types was as follows: A: 36.6% (37/101), B: 56.4% (57/101), C: 3.0% (3/101), D: 4.0% (4/101). The gender (P < 0.001), age (P = 0.041), time engaged in farming (P = 0.040) of the subjects and the length from Z line to fore-tooth (P = 0.001) were correlated with the occurrence of RE. Smoking (OR 1.894, 95% CI 1.207 - 2.974), drinking strong tea (OR 2.900, 95% CI 1.651 - 5.092), using non-steroidal anti-inflammatory drugs (NSAIDs) (OR 2.159, 95% CI 1.166 - 3.997) and loose cardia (OR 13.630, 95% CI 7.37 - 25.19) were risk factors of RE. But there was no relationship between RE and the height, body weight, abdominal circumference, body mass index (BMI), alcohol drinking, special food habit and the history of diabetes, previous abdominal operation, peptic ulcer and atrophic gastritis of the subjects. H.pylori infection rate in the population was 51.3% (273/532). 37.1% (36/97) of RE patients and 54.5% (237/435) of non-RE patients were H.pylori positive (P = 0.002), OR 0.492 (95% CI 0.313 - 0.776). CONCLUSIONS: Male gender, aging, shorter length from Z line to fore tooth, loose cardia and absence of H.pylori infection were correlated with RE. Smoking, drinking strong tea, NSAIDs and long time engaged in farming were risk factors of RE.

The effect of xylitol on Streptococcus mutans in children.

A study was performed on 91 second-grade students from the Los Angeles Unified School District to test the effects of xylitol chewing gum on Streptococcus mutans in the saliva. Saliva was collected from students and tested for the first time using the new University of California, Los Angeles, monoclonal antibody testing method. Students found to have moderate or high levels of salivary S. mutans were administered four tablets/day of xylitol gum for three weeks. The levels of S. mutans in the saliva of children in the high caries index subgroup decreased by 61.7 percent. Xylitol can be dispensed in a public school setting by school nurses and can be a very safe, efficient and inexpensive preventative measure for children at high risk for dental caries.

In situ and non-invasive detection of specific bacterial species in oral biofilms using fluorescently labeled monoclonal antibodies.

Noninvasive in situ detection of suspected cariogenic bacterial species within dental biofilms could facilitate monitoring of the dynamic change of oral microbial flora and assist in the assessment of the treatment efficacy of therapeutic agents. In this study, we explore the possibility to use three well-characterized monoclonal antibodies (MAbs) against Streptococcus mutans, Actinomyces naeslundii, and Lactobacillus casei to identify these three important members of the oral microbial community in the complex environment of oral biofilms. These MAbs, which were conjugated to different fluorescent labels and visualized with confocal laser scanning microscopy (CLSM), proved to be an useful tool to identify the three species of interest (S. mutans, A. naeslundii, and L. casei) under various experimental conditions including in vitro and in vivo derived oral biofilms. Manifold addition of the MAbs on consecutive days did not alter the biofilm structure thus allowing monitoring of the same biofilm over extended time periods. Using this MAb-based method the effect of sucrose challenge on the biofilm composition and the distribution of S. mutans, A. naeslundii, and L. casei were examined. S. mutans was found to be the predominant species under the various biofilm conditions tested. These studies indicate that MAbs based bacterial detection with CLSM is a versatile tool which permits new insights into the ecology of oral biofilm development.

Measurement for natural dental neck data of normal adults and its clinical significance on guiding implant restoration.

OBJECTIVE: Provide reference basis for the clinical implant restoration to select implant diameter through measuring each data of 7 teeth in the dental neck of bilateral upper and lower jaws of the young volunteers with normal dentition. METHODS: Select 30 healthy young volunteers with complete dentition but no malocclusion, take cone beam CT (CBCT), measure the mesiodistal and buccolingual distance of the tooth root at 1.5 mm from 14 teeth (bilateral upper and lower jaws) to alveolar crest, trace out the outline of each tooth neck in this layer, calculate the cross sectional area and roundness of each tooth neck according to pixel value calibration, and then carry out statistical processing. RESULTS: Complete the data collection and processing of mesiodistal length, buccolingual width, cross sectional area, and cross sectional roundness of the dental neck at 1.5 mm from these seven teeth of the bilateral upper and lower jaws to the alveolar crest of 30 volunteers, and calculate the mean value, variance, and reference value range of medical science of each index. CONCLUSION: CBCT can effectively obtain the image information of the dental neck. Through mimics 10.0 and Photoshop CS3, it is possible to accurately calculate the dental neck length and width, and cross sectional area of each tooth according to CBCT image information. This result can provide reference basis for the implant restoration of the clinical teeth.

Mechanical analysis on individualized finite element of temporal-mandibular joint under overlarge jaw opening status.

BACKGROUND: Analyze the stress status of temporal-mandibular joint (TMJ) of a healthy volunteer under the overlarge jaw opening status through the finite element method, with the purpose of clarifying the loading features of each structure in the joint area, and achieving further understanding of the pathogenesis of the temporomandibular disorders (TMD). METHODS: Collect the CBCT and MRI data of a volunteer respectively under the maximum jaw opening, establish the finite element model (FEM) of TMJ under the maximum jaw opening status through a series of software, image segmentation, rectification, meshing, material evaluation and other related processing, simulate the mechanical environment of this joint area under this status, and analyze the stress status of the articular disc, condyle cartilage, and condyle process. RESULTS: Based on CT and MRI image data, build 3D model and FEM of TMJ, fully simulate the mechanical environment under the large jaw opening status, and calculate the stress value of the articular disc, condyle process and condylar cartilage. CONCLUSIONS: This research result reminds us that the normal people's articular disc are easy to generate stress concentration under large jaw opening, but its stress is far less than the one under the tight biting status. Perhaps the TMJ symptom induced under the large jaw opening status is mainly caused by the displacement of the articular disc. Under the large jaw opening status, the condylar cartilage plays a vital role in dispersing the stress. This method can be applied for carrying out individualized mechanical analysis on the patients with TMD.

Effect of intracanal corticosteroids on healing of replanted dog teeth after extended dry times.

This study investigated the effect of potent intracanal corticosteroids on periodontal healing of replanted avulsed teeth and evaluated the systemic absorption of these corticosteroids. Sixty-seven extracted dog premolar roots were randomly assigned to one of the following groups: groups 1-3 filled with gutta-percha and replanted immediately and after 40 and 60 minutes, respectively; groups 4 and 5 filled with 0.05% clobetasol; and groups 6 and 7 filled with 0.05 % fluocinonide. Groups 4 and 6 were replanted after 40 minutes and groups 5 and 7 after 60 minutes. After 4 months, roots were evaluated histologically for signs of periodontal healing. Roots treated with clobetasol and fluocinonide healed more favorably than roots filled with gutta-percha and were different from each other at 60 minutes. No change in the systemic corticosteroid blood concentration was observed in any group. Corticosteroids were efficacious in the beagle model as intracanal medicaments for promoting favorable postavulsion periodontal healing.

[Study of three dimensional reconstruction and visualization of human mandible].

PURPOSE: This study is designed to reconstruct 3-D digital visible mandibular model using digital human database. METHODS: An appropriate cadaver was fixed, and fused through arterial infusion, then embedded and sliced. The 2-D imaging data of mandible were obtained from this virtual human, and the virtual mandible was reconstructed using Amira software. RESULTS: Complete and accurate data of the mandible sections were collected, with which the virtual mandible was reconstructed three dimensionally. This virtual mandible displayed accurately the anatomical structure of the actual mandible, including the location and direction of the mandibular teeth and the mandibular canal. CONCLUSION: The 3-D mandible was constructed through the database of the digital human. The visible mandibular model will be an important learning tool in oral and maxillofacial anatomy and surgery, diagnosis and operation of mandibular diseases, and mandibular dental implantation.

Comparative analysis of a monoclonal antibody-based Streptococcus mutans detection method with selective culture assays using polymerase chain reaction as a gold standard.

The aim of this study was to compare a recently developed monoclonal antibody (MAb)-based salivary Streptococcus mutans detection method with various selective media using polymerase chain reaction (PCR) as the gold standard. Salivary S. mutans cells were enumerated with a MAb-based method, along with three commonly used selective media, mitis-salivarius-bacitracin agar (MSB), trypticase yeast-extract cystine sucrose bacitracin agar (TYCSB), and glucose-sucrose-potassium tellurite-bacitracin (GSTB) agar. Statistical analysis showed no significant correlations between each method. With PCR as the standard, a MAb-based detection method was found to provide the highest sensitivity (91%) and specificity (96%) among these four methods. This study demonstrates that the MAb-based detection method may provide more accurate enumeration of salivary S. mutans than selective media.

Production and characterization of species-specific monoclonal antibodies against Actinomyces naeslundii and Lactobacillus casei.

Dental caries is a disease induced by a few cariogenic bacterial species. Quantitative detection of these cariogenic bacteria could provide useful information for caries risk assessment. In this study, we developed highly species-specific monoclonal antibodies (MAbs) against the type strains of Actinomyces naeslundii ATCC 12104 and Lactobacillus casei ATCC 11578. Assayed with immunoprecipitation and immunofluorescent microscopy, these antibodies showed high sensitivities and specificities in detecting A. naeslundii and L. casei in saliva. Examining 100 saliva samples using these MAb-based techniques, we found that the number of A. naeslundii in saliva ranges from 0.5 x 10(4) to 4.8 x 10(5) and that the number of L. casei in saliva ranges from 1 x 10(4) to 1.2 x 10(6). With fluorescent imaging techniques and confocal laser scanning microscopy (CLSM), these antibodies were used to visualize A. naeslundii and L. casei within dental plaques derived from stimulated whole human saliva in vitro. The study demonstrated that these MAbs were also able to effectively detect A. naeslundii and L. casei in plaque.

Analyses of Streptococcus mutans in saliva with species-specific monoclonal antibodies.

Three species-specific monoclonal antibodies (MAbs) against Streptococcus mutans were used to detect and quantify S. mutans levels in saliva. This study shows that MAb-based salivary S. mutans tests exhibit significantly higher specificity and sensitivity than the commonly used selective culture method. Examination of nearly 2,000 human saliva samples shows that S. mutans counts in human saliva vary from less than 10,000 to a high 36 million cells/mL. Over 15% of the saliva samples examined have salivary S. mutans counts over 500,000 cells/mL. When saliva samples were collected at different time points during a day, the number of salivary S. mutans in the same human subject varied, especially before and after sugar uptake. Additionally, data obtained from stimulated versus unstimulated saliva in the same human subjects differed greatly and appear to be completely uncorrelated. This study provides useful information and tools for analyzing the role of S. mutans in human dental caries.